Theory.
When different war ministries contracted for ersatz helmets in1914. They flailed with different designs and materials. Priority was numbers. Smaller states had wappen shortages. Those in the Prussian army fell back on Prussian wappen but the smaller kingdoms made a decision to deploy sans wappen. So my Thought is that these were ordered and accepted from a cork producer. Bavaria does not seem to have had this problem and most of my documentation come from there. It goes back to understanding of the Probe system and the excesses of post mobilization procurement. we could prove this with the 1914 XII corps AVB. I do not know of one and as this is theory I will not enter into a first year law school debate about things Probe.